Automatic phase control for traffic lights



United States Patent 3,149,306 AUTOMATIC PHASE CONTROL FOR TRAFFICLIGHTS John C. Lesher, Erie, Pa., assignor to Rad-O-Lite, Inc., Erie,Pa., a corporation of Pennsylvania Filed May 18, 1962, Ser. No. 195,8764 Claims. (Cl. 340-41) This invention relates to an automatic phasecontrol for trafiic lights.

The object of the present invention is to provide an automatic controlcircuit for traffic lights in which the periods of illumination of thethree lights may overlap each other in variable degrees or may followeach other in sequence without either overlapping or interruption.

Another object of the present invention is to provide an automaticcontrol circuit for trafiic lights in which the master control for thethree lights is a simple switch as distinguished from the rotary slipring switches or master relays commonly used to control the timingcycle.

A further object of the present invention is to provide an automaticcontrol circuit for trafiic lights which circuit includes onlyconventional circuit component such as capacitors, rectifiers, relaysand resistors.

Still other objects, advantages and improvements will become apparentfrom the following specifications, taken in connection with theaccompanying drawing; in which the single figure represents the circuitdiagram.

In the circuit diagram, red, amber, and green trafiic signal lights areshown at 10, 11 and 12, respectively. For simplicity only three (3)lights for controlling traffic on a single street are shown. It will beobvious however that the circuit may be duplicated for a cross street atan intersection. The circuit is energized from an AC. power line (notshown) which is connected to input terminals 13 and 14.

The master control for the three lights 10, 11 and 12 is a double pole,single throw switch SW. This switch has an Off contact and an Oncontact. As here shown, the switch is representative of the front endtiming circuit of applicants Rad-O-Lite ETC-400 Controller of applicantscopending US. application Serial No. 164,047. The power input terminal13 is connected by a conductor 15 to the arm of the switch. A commonreturn conductor 16 for the circuit is connected to the power in putterminal 14.

The three lights 10, 11 and 12 are controlled jointly by a pair ofrelays RY1 and RY-2. The relay RY-l has two armatures 23 and 27, whichare interconnected by a link 25. In the position shown, the relay isdeenergized and the armature 23 is closed on a circuit making contact 22and the armature 27 on a rest contact 26. When the relay RY-l isenergized, the armature 23 is closed on a rest contact 24 and thearmature 27 on a circuit making contact 28.

The relay RY-2 is a single pole, double throw relay, having an armature40 and dual contacts 39 and 41, both of which are circuit making andbreaking contacts. In the position shown, the relay is de-energized andthe armature 40 is closed on the contact 39; when the relay isenergized, the armature is closed on the contact 41.

The energizing circuit of the relay RY-l is from the On contact of theswitch SW over a conductor 17, through a current limiting resistor R-1and a diode rectifier D-1, the winding of the relay, and over aconductor 18 to the common return conductor 16. A capacitor C-1 isconnected across the winding of the relay by conductors 19 and 20.

The energizing circuit of the relay RY-2 is over a con- 3,149,306Patented Sept. 15, 1964 ductor 21, which is connected at one end to theconductor 15 ahead of the switch SW-1 and at its other end to botharmatures 23 and 27 of the relay RY-l, the contact 28 of the latterrelay, over conductors 30 and 31, through a current limiting resistor R2and a diode rectifier D-2, over a conductor 33, through a currentlimiting resistor R3, over a conductor 37, through the winding of therelay RY-Z, and over a conductor 38 to the common return conductor 16. Acapacitor C-2 is connected across the second current limiting resistorR3 and the winding of the relay by conductors 35 and 36. The energizingcircuit for the relay RY-2 is also the first load circuit for the relayRY-l.

A time control for the relay RY-2 is comprised by a current limitingresistor R-4 and a fixed resistor R-S, which are connected in seriesbetween the conductors 31 and 33 and the common return conductor 16, anda variable resistor R-6, which is connected in parallel with the fixedresistor R-S. The common conductor 16 is connected at its end to the arm34 of this variable resistor.

The second load circuit of the relay RY-l is from the input terminal 13over the conductor 21, to the first armature 23 and fixed contact 22 ofthe relay RY-l, over the conductor 29 to the armature 40 and fixedcontact 39 of the relay RY-2, over the conductor 42 to the red light 10,and over the conductor 43 and the common return conductor 16 to theterminal 14. This is also the first load circuit for the relay RY-2.

The third load circuit for the relay RY-l is from the input terminal 13over the conductor 21 to the second armature 27 and fixed contact 28 ofthe relay, over the conductor 30 and the conductor 31 to the green light12, and over the conductor 32 and the common return conductor 16 to theinput terminal 14.

The fourth load circuit of the relay RY-l is from the input terminal 13over the conductor 21 to the armature 23 and fixed contact 22 of therelay, over the conductor 29 to the armature 40 and fixed contact 41 ofthe relay RY-2, over the conductor 44 to the amber light 11, and overthe conductor 45 and common return conductor 16 to the terminal 14.

The circuit has been found to operate in a satisfactory manner with thefollowing values for the circuit components:

C-1 mfd., volts. C-Z rnfd., 150 volts. R-l 2.2 kilo-ohms.

R-2 470 ohms.

R-3 8.2 kilo-ohms. R-4 5.6 kilo-ohms.

R-S 47.0 kilo-ohms. R-6 50.0 kilo-ohms.

It will be recognized however that different values may, for the abovecomponents, have to be employed according to the constants of therelays.

In the sequence of operation let it be assumed that the relays RY-l andRY-2 are in the de-energized condition, as shown in FIGURE 1. The redlight 10 is on.

The switch SW is now moved to the On position. The red light 10 nowimmediately goes out and the green light 12 comes on. The alternating117 voltage is applied over the conductor 17, through the currentlimiting resistor R-1 and diode rectifier D-1 and conductor 19 to thecapacitor C-1, and over the conductor 20 and the common return conductor16. The diode rectifier D-1 provides positive half wave rectificationand the capacitor C-l is positively charged. The relay RY-1 is energizedat the same time and contacts 22 and 23 are broken and saaasoe contacts27-28 are made. The breaking of the contacts 22 and 23 opens the circuitthrough the red light 10 and it goes out. At the same time the making ofthe contacts 27 and 28 completes the circuit for the green light 12 andit comes on. The relay RY-l continues to be energized as long as theresistor R-1 and the diode rectifier D-l pass energy to the capacitor C4and the latter remains charged.

When the contacts 27 and 28 of the relay RY1 were made they also passedthe alternating 117 voltage to resistor R-2 and diode rectifier D2. Thelatter provides positive half wave rectification. The positive halfwaves are impressed across the capacitor C2 over the conductors 33 and35 and the conductor 36 and common return conductor 16, thereby chargingthe capacitor C2 positively. At the same time the voltage developedcauses a current to flow through the resistor R-3, the conductor 37, thewinding of the relay RY-2, and through the conductor 38 and the commonreturn conductor 16. The relay RY-Z is energized and the contacts 39 and40 are broken and the contacts 40 and 41 are made, and the relay RY-Z isheld energized as long as the capacitor C2 is charged. It will benoticed that the relay RY-l is energized before the relay RY-2, sincethe normally open contacts 27 and 28 of the relay RY1 are in theenergizing circuit of relay RY-2 and the closing of these contactsdepends upon the time delay factor of the relay RY1.

In the sequence of operations thus far described, the red light 10 hasgone out and the green light 12 has come on.

The switch SW is now turned to the Off position. The green light 13 nowgoes off, the amber light 11 comes on, and then goes off, and the redlight 10 comes on and stays on.

When the switch SW is moved to the Off position, the energizing circuitof the capacitor -1 is opened and the relay RY-l is de-energized almostimmediately. The armature 27 moves ofi the fixed contact 28 and thecircuit of the green light 13 is opened. At the same time the armature23 closes on the fixed contact 22, passing the 117 alternating voltageto the armature 40 and fixed contact 41 of the relay RY-2. Thiscompletes the circuit for the amber light 11. When the armature 27 wasseparated from the fixed contact 28 of the relay RY-1, the circuitthrough the resistor R-2 and the diode rectifier D-2 and capacitor C2began discharging from the negative side over the conductor 36, thecomon return conduc tor 16, the variable time control comprised by theresistors R- and R-6 through the current limiting resistor R-4 and overthe conductors 33 and 35, to the positive side. Relay RY-2 will remainenergized and hold the amber light 19 on, until the capacitor C2 hasbeen discharged through the variable time control comprised by theresistors R5 and R-6. When the capacitor C2 is discharged, relay RY-2 isde-energized and its armature 40 closes on the fixed contact 39. Thisagain completes the circuit of red light and the light comes on.

If the switch SW is moved again to the On position, the entire cycle ofoperation will be repeated.

Having now fully described by invention, What I claim as new and usefuland desire to secure by Letters Patent of the United States is:

1. An automatic phase control system for sequential operation of trafiiclights from an alternating current power source comprising circuitmeans, an alternating current energizing means therefor including dualterminal means, a cycle controlled single pole double-throw switch meansoperatively connected to said current energizing means, rectifiedcurrent means including resistive current limiting means energized bysaid switch means, a first relay means including dual armature means anddual contacts therefor, one armature and contact being normally closedwith one armature and a normally open contact cooperating with the otherarmature being normally open with respect to said armature, saidarmature cooperating with said switch means, an energizing rectifiedcurrent means for said first relay means from one terminal of thealternating power source through said switch means and the winding ofsaid relay to the other terminal of the power line, a second relay meanshaving a single armature means and dual contact means, one contact meansbeing normally closed with respect to said armature means and onecontact means being normally open with respect to said armature means, asecond rectifying current means connected to said. alternating currentenergizing means independently of said switch means operativelyenergizing said second relay means, said normally closed contact meansof said first relay means sequentially connecting one terminal of saidalternating current power line to a red traffic signal and to the otherterminal means of said power line means, said open contact means of saidfirst relay means consequently connecting one terminal of said powerline means to a green light signal means and to the other terminal ofsaid power line means, a resistive time delay capacitative dischargecircuit operably connecting the armature winding of said first relaymeans to a timing circuit and capacitative charging circuit in parallelwith the armature Winding means of said second relay means, said secondrelay means being energized by the discharge of said capacitor meansactuating said open contact means of said second relay means tosequentially connect, energize and display an amber light traffic signalmeans across both terminals of said power line means.

2. An automatic electrical phase control system for sequence operationof a plurality of traffic signal lights from a common alternatingcurrent energy source having two output terminals comprising, circuitmeans, alternating current energy means, a first relay means andenergizing circuit means therefor including switch means interconnectingone side of said energy means to a current limiting resistor means inseries with a first diode rectifier means connected in parallel with acapacitor and winding of the first relay means connected in parallelcircuit arrangement with the other side of said energy source; a secondrelay means and energizing circuit means comprising conductor meansconnecting one of said output terminals of said energy means to theactuated armature contact means of said first relay means connected inparallel with a second capacitor means and current limiting resistormeans connected to the winding of said second relay means, said secondcapacitor means and said winding being connected in parallel to theother energy output terminal; energized circuit means for sequentiallycontrolling three trafiic signal lights means in a predetermined patternjointly controlled by said first relay means and said second relay meanscomprising circuit means interconnecting one terminal of saidalternating current energizing means to the closed contact of saidunenergized first relay means connected to the closed contact of saidsecond relay means connected to a red signal trafiic light means to theother terminal of said energy means; circuit means comprising switchmeans interconnecting one termnal of said energy means to a secondclosed contact of said energized first relay means connected to a greentraflic signal light means to the other terminal of said alternatingenergy means; and circuit means comprising switch contact meansinterconnecting one terminal of said energy means to a closed contact ofsaid unenergized first relay means connected to a closed contact of saidunenergized second relay means connected to an amber traific lightsignal means to the other terminal of asid energy source to sequentiallyactuate said plurality of trafiic light signals.

3. An automatic electrical phase control system for sequence operationof a plurality of trafiic signal lights from a common alternatingcurrent source having two output terminals, as in claim 2, wherein saidcircuit means comprises control circuit means to de-energize the redtraflic light signal means and energize the green traific light signalmeans, and timing circuit means wherein said first relay means remainsenergized by said charged first capacitor means and said secondrelaymeans remains deenergized to de-energize said green trafiic lightsignal means and energize said amber traflic light signal means.

4. An automatic electrical phase control system for sequence operationof a plurality of trafiic signal lights from a common alternatingcurrent source having two output terminals as in claim 3, wherein saidtiming circuit means comprises variable resistive current flow meanscooperating with said charged first capacitor means to control theperiod of energizing said amber traflic light signal means.

References Cited in the file of this patent UNITED STATES PATENTS

1. AN AUTOMATIC PHASE CONTROL SYSTEM FOR SEQUENTIAL OPERATION OF TRAFFICLIGHTS FROM AN ALTERNATING CURRENT POWER SOURCE COMPRISING CIRCUITMEANS, AN ALTERNATING CURRENT ENERGIZING MEANS THEREFOR INCLUDING DUALTERMINAL MEANS, A CYCLE CONTROLLED SINGLE POLE DOUBLE-THROW SWITCH MEANSOPERATIVELY CONNECTED TO SAID CURRENT ENERGIZING MEANS, RECTIFIEDCURRENT MEANS INCLUDING RESISTIVE CURRENT LIMITING MEANS ENERGIZED BYSAID SWITCH MEANS, A FIRST RELAY MEANS INCLUDING DUAL ARMATURE MEANS ANDDUAL CONTACTS THEREFOR, ONE ARMATURE AND CONTACT BEING NORMALLY CLOSEDWITH ONE ARMATURE AND A NORMALLY OPEN CONTACT COOPERATING WITH THE OTHERARMATURE BEING NORMALLY OPEN WITH RESPECT TO SAID ARMATURE, SAIDARMATURE COOPERATING WITH SAID SWITCH MEANS, AN ENERGIZING RECTIFIEDCURRENT MEANS FOR SAID FIRST RELAY MEANS FROM ONE TERMINAL OF THEALTERNATING POWER SOURCE THROUGH SAID SWITCH MEANS AND THE WINDING OFSAID RELAY TO THE OTHER TERMINAL OF THE POWER LINE, A SECOND RELAY MEANSHAVING A SINGLE ARMATURE MEANS AND DUAL CONTACT MEANS, ONE CONTACT MEANSBEING NORMALLY CLOSED WITH RESPECT TO SAID ARMATURE MEANS AND ONECONTACT MEANS BEING NORMALLY OPEN WITH RESPECT TO SAID ARMATURE MEANS, ASECOND RECTIFYING CURRENT MEANS CONNECTED TO SAID ALTERNATING CURRENTENERGIZING MEANS INDEPENDENTLY OF SAID SWITCH MEANS OPERATIVELYENERGIZING SAID SECOND RELAY MEANS, SAID NORMALLY CLOSED CONTACT MEANSOF SAID FIRST RELAY MEANS SEQUENTIALLY CONNECTING ONE TERMINAL OF SAIDALTERNATING CURRENT POWER LINE TO A